Differential enhancement of breast cancer cell motility and metastasis by helical and kinase domain mutations of class IA phosphoinositide 3-kinase.
Differential enhancement of breast cancer cell motility and metastasis by helical and kinase domain mutations of class IA phosphoinositide 3-kinase.
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DOI：
10.1158/0008-5472.can-09-1968
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发表时间：
2009-12-01
期刊：
影响因子：
11.2
通讯作者：
Backer JM
中科院分区：
文献类型：
--
作者：
Pang H;Flinn R;Patsialou A;Wyckoff J;Roussos ET;Wu H;Pozzuto M;Goswami S;Condeelis JS;Bresnick AR;Segall JE;Backer JM
IA类(p85/p110)PI3-激酶在调节细胞生长、存活和运动中发挥重要作用。IA类催化亚单位(PIK3CA)的p110α亚基的激活突变在人类癌症中很常见。这些突变导致培养细胞的增殖和转化增加，但它们对细胞运动和肿瘤转移的影响尚未得到评估。我们利用慢病毒介导的基因转移和敲除获得了稳定的mda-MB-231细胞，其中内源性的人p110α被野生型牛p110α或两个最常见的激活p110α突变体取代：螺旋域突变体E545K和激酶域突变体H1047R。PI3K/Akt通路在表达生理水平的螺旋结构域或激活域突变体的细胞中被过度激活。在体外，表达这两种突变体的细胞表现出更强的运动能力，但只有表达螺旋结构域突变体的细胞在趋化试验中表现出更强的方向性。在SCID小鼠中，与表达野生型p110α的肿瘤相比，表达任一突变体的异种移植瘤显示出更高的肿瘤生长速度。然而，与表达野生型p110α或激酶结构域突变的肿瘤相比，尾静脉注射后，表达p110α螺旋结构域突变的肿瘤细胞进入血液的肿瘤细胞显著增加，进入肺的肿瘤细胞外渗入肺的肿瘤细胞显著增加。我们的观察表明，与基因相同背景下的激活域突变相比，p110α螺旋域突变的表达产生了更严重的转移表型。
Class IA (p85/p110) PI 3-kinases play a major role in regulating cell growth, survival, and motility. Activating mutations in the p110α isoform of the class IA catalytic subunit (PIK3CA) are commonly found in human cancers. These mutations lead to increased proliferation and transformation in cultured cells, but their effects on cell motility and tumor metastasis have not been evaluated. We used lentiviral-mediated gene transfer and knockdown to produce stable MDA-MB-231 cells in which the endogenous human p110α is replaced with either wild type bovine p110α, or the two most common activating p110α mutants: the helical domain mutant E545K and the kinase domain mutant H1047R. The PI3K/Akt pathway was hyperactivated in cells expressing physiological levels of helical or kinase domain mutants. Cells expressing either mutant showed increased motility in vitro, but only cells expressing the helical domain mutant showed increased directionality in a chemotaxis assay. In SCID mice, xenograft tumors expressing either mutant showed increased rates of tumor growth as compared to tumors expressing wild type p110α. However, tumors expressing the p110α helical domain mutant showed a marked increase in both tumor cell intravasation into the blood, and tumor cell extravasation into the lung after tail vein injection, as compared to tumors expressing wild type p110α or the kinase domain mutant. Our observations suggest that when compared to kinase domain mutations in a genetically identical background, expression of helical domain mutants of p110α produce a more severe metastatic phenotype.